Dynamic cooling of tissue for radiation treatment

ABSTRACT

The present invention features various methods and systems for performing radiation treatment of skin in connection with dynamic cooling of tissue, while minimizing or preventing occurrence of light flash during the treatment.

This application claims priority under 35 U.S.C § 120 as a continuationof U.S. Pat. No. 09/240,464, filed Jan. 29, 1999 now U.S. Pat. No.6,200,308.

FIELD OF THE INVENTION

This invention relates to radiation treatment of tissue. Morespecifically, this invention relates to an improved dynamic coolingdevice and method in connection with radiation treatment of tissue.

BACKGROUND

Radiation surgery has been successfully employed to treat tissue.Radiation surgery involves the application of radiation to tissue toremove or alter the condition of the tissue. Radiation can be generatedin the form of light from a laser or a lamp such as a flash lamp, orheat from an RF source. Alternatively, radiation can be generated in theform of microwaves or ultrasound.

Laser surgery has been successfully employed to remove hair and to treatskin abnormalities such as vascular lesions. For example, in performinga laser surgery, a beam of laser light having a selected wavelength isapplied to a targeted region of the skin to selectively destroy thecutaneous blood vessels or melanin depending on the application. Whenremoving unwanted hair, a beam of laser light is applied to the targetedskin. The light penetrates deep into the dermal tissue region, where thelight is absorbed by peri-follicular melanin, reaching the follicle,bulb, bulge, and vascular supply to eliminate unwanted hair and impedeits growth. In treating vascular lesions such as a port wine stain,laser light is preferentially absorbed by the hemoglobin which is themajor chromophore in the blood in the ectatic capillaries in the upperdermis. The light energy is converted to heat, causing thermal damageand thrombosis in the targeted vessels.

Laser treatments, however, can be painful to a patient. To reduce pain,the cooling of tissue has been employed during laser treatment. U.S.Pat. No. 5,814,040, incorporated herein by reference, describes coolingan epidermal tissue region while performing selective photothermolysisof selected buried chromospheres in biological tissues using a laser.This cooling procedure is known as dynamic cooling. In this procedure,an epidermal tissue region is cooled by spraying with a cryogen toestablish a predetermined dynamic temperature profile. The epidermal andunderlying dermal tissue regions are subsequently irradiated tothermally treat the dermal tissue region while leaving the epidermaltissue region substantially undamaged. Cooling the epidermal tissueregion reduces pain suffered by the patient during the procedure, andpermits application of higher dosage radiation.

The GentleLase™ laser treatment system for hair removal and treatment ofvascular lesions manufactured by Candela Corporation (Wayland, Mass.)employs dynamic cooling technology. The GentleLase™ laser treatmentsystem includes a control unit and a handpiece. The control unitincludes a flashlamp excited long-pulse alexandrite laser, a source ofHFC 134a liquid cryogen, and electronics for controlling the system. Thehandpiece receives the laser light and the cryogen from the control unitthrough a cable which includes an optical fiber, wires, a delivery tubeand an electronically controlled valve. The handpiece delivers thecryogen and the laser to tissue being treated. In the procedure, ahighly focused spray of HFC 134a cryogen is applied on the patient'sskin for 20-100 milliseconds, and after waiting 0-3 milliseconds, thelaser pulse is applied to the patient's skin.

Clinical tests have shown that in order to achieve a desirable lowtemperature profile (e.g. −30° C. to 25° C.) in the epidermal tissueregion, a waiting period after applying the cryogen of up to about 250milliseconds is needed before applying the laser pulses. The desirablelow temperature profile can vary depending on the skin tone of thepatient and the objective in cooling. Only a few degrees below normalskin temperature may be sufficient when treating a patient having alight skin tone. On the other hand, when treating a patient having adark skin tone, cooling to −30° C. may be desired. One problemencountered during dynamic cooling of an epidermal tissue region with awaiting period of up to about 250 milliseconds is that a bright lightflash not associated with normal laser treatment has been observedduring the procedure. The bright light flash resembles a flame, andtends to frighten the patients and interfere with light transmission.Therefore, a shorter waiting period of about 3 milliseconds which may beinsufficient to obtain an optimal low temperature profile, is presentlyused to suppress the abnormal light flash. It is expected that similarflashing problems can occur during radiation treatment using otherradiation sources.

SUMMARY OF THE INVENTION

The present invention provides methods and systems for performingradiation treatment of skin, while dynamic cooling the epidermal tissueregion and minimizing or preventing light flashes from occurring. Theradiation treatment can include removal of hair or treatment ofpigmentation abnormalities (e.g. vascular lesions, tattoos, etc.).

In one aspect, the invention features a method for performing radiationtreatment of skin having an epidermal tissue region and a dermal tissueregion. In one embodiment, the epidermal tissue region is cooled byapplying a cryogenic fluid to the epidermal tissue region. A gas flow isdirected in the general direction of the epidermal tissue region toremove at least a portion of the cryogenic fluid applied to theepidermal tissue region. The skin is irradiated with a radiation sourceto treat the dermal tissue region subsequent to removing at least aportion of the cryogenic fluid. This method has been found to minimizeor prevent an abnormal light flash from occurring during the lasertreatment.

In one detailed embodiment, a non-reactive gas flow is directed in thegeneral direction of the epidermal tissue region. The non-reactive gasflow can comprise air, nitrogen, or CO₂. In another embodiment, a gasflow is directed in the general direction of the epidermal tissue regionprior to and during application of the cryogenic fluid. In anotherdetailed embodiment, skin is irradiated between 5 and 500 milliseconds,and more preferably between 50 and 200 milliseconds after applying thecryogenic fluid to the epidermal tissue region. In another detailedembodiment, a cryogenic liquid is applied to the epidermal tissue regionand a cryogenic vapor formed, through the evaporation of the cryogenicliquid, is removed. In yet another detailed embodiment, the cryogenicfluid comprises a fluorocarbon compound having a ratio of fluorine tofluorine and hydrogen which is greater than about 0.75. The fluorocarboncompound is selected from a group consisting of: tetrafluoromethane;hexafluoroethane; octafluoropropane; chlorotrifluromethane;chloropentafluoroethane; dichlorodifluoromethane;1,2-dichlorotetrafluoroethane; 1,1,1,2,3,3,3,-heptafluoropropane;pentafluoroethane; 2-chloro-1,1,1,2-tetrafluoroethane; trifluoromethane;1,1,1,2,3,3-hexafluoropropane; and 2,2-dichloro-1,1,1-trifluoroethane.

In another embodiment, the method of performing radiation treatment ofskin comprises the following steps. A first pulse of cryogenic fluid isapplied to an epidermal tissue region for a first time period. Afterwaiting a delay period of a predetermined time interval, a second pulseof cryogenic liquid is applied to the epidermal tissue region for asecond time period. The delay period is sufficient to allow the firstpulse of cryogenic fluid to cool the epidermal tissue region to reach adesired temperature profile. The skin is irradiated to treat anunderlying dermal tissue region either during or immediately afterapplication of the second pulse of cryogenic liquid, thereby minimizingor preventing an abnormal light flash from occurring during treatment.

In one detailed embodiment, a first pulse of cryogenic liquid is sprayedto the epidermal tissue region for a time period in the range from 10milliseconds to 150 milliseconds, and a second pulse of cryogenic liquidis sprayed to the epidermal tissue region for a time period in the rangefrom about 5 milliseconds to about 20 milliseconds after waiting a delayperiod in the range from about 10 milliseconds to about 500milliseconds. In another detailed embodiment, the skin is irradiatedwithin 5 milliseconds of applying the second pulse of cryogenic liquid.In still another detailed embodiment, the skin is irradiated within 3milliseconds of applying the second pulse of cryogenic liquid.

In another aspect, the invention features an apparatus having aradiation source for performing a radiation treatment of skin having anepidermal tissue region adjacent a dermal tissue region. The apparatusincludes a first fluid delivery device for delivering a cryogen to theepidermal tissue region, a device for delivering radiation to the skinto treat the dermal tissue region, and a second fluid delivery devicefor delivering a gas flow in the general direction of the epidermaltissue region to inhibit the chemical reaction leading to the brightlight flash. The device for delivering radiation can be an opticaldevice for delivering light.

In one embodiment, the second fluid delivery device surrounds theoptical device. In another embodiment, the second fluid delivery deviceis substantially collinear with the first fluid delivery device. Inanother embodiment, the second fluid delivery device surrounds the firstfluid delivery device. In another embodiment, the second fluid deliverydevice comprises a plurality of passageways substantially surroundingthe optical device. In still another embodiment, the apparatus furtherincludes a body, and the second fluid delivery device comprises an inletfor introducing the gas to the body and an outlet for removing the gasfrom the body. The gas entering the body through the inlet circulateswithin the body.

In another aspect, the invention features a handpiece attachable to alaser for performing laser treatment of skin. The handpiece includes abody, an optical device disposed inside the body for delivering a lightbeam from the laser to the skin to treat a dermal tissue region, a valvedisposed inside the body for delivering a cryogen to an epidermal tissueregion above the dermal region, and a fluid delivery device disposedinside the body for delivering a gas flow in the general direction ofthe epidermal tissue region to remove at least a portion of the cryogendelivered to the epidermal tissue region.

In one embodiment, the fluid delivery device substantially surrounds theoptical device. In another embodiment, the valve is coupled to a cryogentube and the fluid delivery device is substantially parallel to thecryogen tube. In another embodiment, the fluid delivery device comprisesa plurality of passageways substantially surrounding the optical device.In still another embodiment, the valve is coupled to a cryogen tube andthe fluid delivery device substantially surrounds the cryogen tube. Instill another embodiment, the fluid delivery device includes an inletfor introducing the gas to the body and an outlet for removing the gasfrom the body. The gas introduced to the body through the inletcirculates within the body.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention is described with particularity in the appended claims.The above and further advantages of this invention may be betterunderstood by referring to the following description taken inconjunction with the accompanying drawings.

FIG. 1 shows a schematic diagram of an embodiment of a radiation systemwhich provides dynamic cooling.

FIG. 2 shows a cross-sectional view of an embodiment of a handpiece ofthe radiation treatment system of FIG. 1.

FIGS. 3A-3B show cross-sectional views of other embodiments of ahandpiece of the radiation treatment system of FIG. 1.

FIGS. 3C-3D show perspective views of other embodiments of a handpieceof the radiation treatment system of FIG. 1.

FIG. 4A shows a cross-sectional view of an embodiment of a control unitof the radiation treatment system of FIG. 1.

FIG. 4B shows a cross-sectional view of another embodiment of a controlunit of the radiation treatment system of FIG. 1.

FIG. 5 shows a flow chart illustrating one embodiment of a method ofperforming radiation treatment of skin.

FIG. 6 shows a flow chart illustrating another embodiment of a method ofperforming radiation treatment of skin.

FIG. 7 shows a flow chart illustrating another embodiment of a method ofperforming radiation treatment of skin.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a laser system 10 includes a control unit 20, and ahandpiece 30. The control unit 20 includes a source of cryogen 22, alaser source 24, a source of gas 26, a power source 28 and electronics29. The cryogen 22 is typically stored under pressure as a liquid. Theradiation source 24 can be a laser source. In other embodiments, otherlight sources such as a flashlamp can be used to generate light.Alternatively, the sources which generate heat, microwave or ultrasoundwaves may be used. The source of gas 26 can be a non-reactive gas suchas air or nitrogen. The power source 28 supplies power to initiate andrun the system 10, and the electronics 29 control the application of thecryogen, the radiation, and the gas to a patient. The position of eachcomponent of the control unit 20 shown in FIG. 1 is exemplary only, andthe components of the control unit 20 and handpiece 30 may be arrangedaccording to other configurations.

Referring to FIG. 2, the handpiece 30 includes a handpiece body 32. Agas line 34 delivers gas from the gas source to the handpiece 30. Inthis embodiment, a fiber optic cable 36 delivers light from the source24 to the handpiece 30. A cable 38 delivers cryogen from the cryogensource 22 to the handpiece 30. The cable 38 includes an electrical wire38 a which control opening and closing of a valve 40 located inside thehandpiece body 32, and the cryogen delivery tube 38 b. When the valve 40is open, pulses of cryogen are released through the narrow metal cryogentube 42. The cryogen tube 42 is angled to direct the cryogen pulses inthe general direction of where a laser beam interacts with the skin.Laser light travels through the fiber optic cable to a fiber assembly 46located inside the handpiece body 32. The fiber assembly 46 includesoptics for focusing the laser light. The focused laser light passesthrough a glass window 48 and forms a beam path 50. The beam of laserlight can be applied as pulses. Gas flows through the gas line 34 and agas supply tube 52 located inside the handpiece body 42. In theembodiment of FIG. 2, the gas supply tube 52 surrounds the fiberassembly 46.

Referring to FIGS. 3A-3D, gas can be applied using other hardwareconfiguration. In the embodiment of FIG. 3A, the gas supply line 34 acontinues through the handpiece body 32 a, and gas is released throughthe gas dispenser 52 a which is substantially parallel with the cryogentube 42 a. In this embodiment, gas and cryogen are releasedsubstantially co-linearly. In the embodiment of FIG. 3B, gas flowsthrough the gas supply line 34 b and a gas inlet 60 b and floods intothe handpiece body 32 b. The gas flooded into the handpiece body 32 bcirculates within the handpiece body 32 b and cools the body 32 b, whichmay have been heated from the fiber assembly and light reflected fromthe skin. The gas is released through the gas outlet or the gasdispenser 52 b. In the embodiment of FIG. 3C, a gas supply tube 52 csurrounds the cryogen tube 42 c, such that gas surrounds the cryogenwhen they are simultaneously released from the handpiece 32 c. In theembodiment of FIG. 3D, the handpiece 32 d includes multiple gas outlets52 d surrounding the fiber assembly (not shown). When the gas and thelaser beam are simultaneously applied, the gas substantially surroundsthe laser beam.

Referring to FIG. 2, the handpiece 30 further includes a button 54 whichcontrols a switch 56. The switch 56 activates delivery of the laser, thecryogen and the gas. The handpiece 30 further includes a distance gauge58. The distance gauge 58 comes in contact with the patient's tissueduring laser treatment. The distance gauge 58 provides a predetermineddesired distance between the handpiece 30 and the tissue of the patient.This predetermined distance controls the diameter of the laser beam 50.Each of the gas line 34, the optical cable 36, the electrical wire 38 a,and the cryogen delivery tube 38 b includes a connector 41 a-41 drespectively, for connecting to the control unit 20 shown in FIG. 1.

In one detailed embodiment, the laser source comprises a flashlampexcited long-pulse alexandrite laser. The laser pulses can have arepetition rate of one hertz (Hz) and a duration of 3 milliseconds(msec). The spot sizes can vary depending on the application. In oneexample, the spot sizes varies from 8 millimeters (mm) to 15 millimeters(mm). For an 8 mm spot size, the fluence can range from 20-100 J/cm².For a 10 mm spot size, the fluence can range from 20-60 J/cm². For a 12mm spot size, the fluence can range from 6-40 J/cm². For a 15 mm spotsize, the fluence can range from 6-30 J/cm².

In one detailed embodiment, the controller 60 includes an air compressor62, and an air reservoir 64 as shown in FIG. 4A. In this embodiment, airfrom the reservoir 64 passes through an air filter and water trap 66, aflowmeter and actuator 68, and an on/off valve 69. Air passing throughthe filter and water trap 66, and the flowmeter and actuator 68 ischilled with an air chiller 65. The actuator 68 and the on/off valve 69control application of air. The valve 69 provides intermittent air flow.Alternatively a reservoir 72 external to the controller 70 can be usedto store air as shown in FIG. 4B. In this embodiment, the compressor maynot be needed. In another detailed embodiment, a continuous air flow maybe applied. In this embodiment, application of air is controlled by anactuator 68 without the valve 69.

As described previously, an abnormal light flash has been observed whenan epidermal tissue region is cooled with a cryogen prior to applicationof laser pulses. The light flash is more prominent as the time delaybetween the application of the cryogen and the laser pulses increases.

Although the exact nature of what causes light flashing is not known, alight flash has been observed where a combination of an initiator, laserpulse, and a cryogenic vapor exists. An initiator is a dark object, suchas hair. It is believed that flashing may be caused by heating theinitiator with the laser, which releases energy that is subsequentlyabsorbed by cryogenic vapor molecules, causing the molecules tochemically react. Chemical reaction of cryogenic vapor molecules createsCarbon soot as a by product. Since Carbon soot is dark in color, itfurther functions as an initiator propagating additional light flashes.Flashing has been observed when R134a (tetrafluroethane) has been usedas a cryogen.

The present invention features several methods of performing lasertreatment of skin, while minimizing or preventing occurrences of lightflash. In one embodiment, the method includes the steps shown in FIG. 5,which uses the system described in FIGS. 1 through 4B. According to thismethod, an epidermal tissue region is cooled by applying a cryogenicfluid to the epidermal tissue region (step 100). A gas flow is appliedin the general direction of the epidermal tissue region to remove atleast a portion of the cryogenic fluid applied to the epidermal tissueregion (step 120). The gas flow rate is greater than about 10liters/minute. The skin is irradiated with a laser beam, to treat theunderlying dermal tissue region (step 120).

In this embodiment, removing at least a portion of the cryogenic fluidprior to irradiating the dermal tissue region prevents light flash fromtaking place (step 120). The cryogenic fluid can be removed by applyingor blowing a non-reactive gas to the epidermal tissue region. An exampleof an appropriate non-reactive gas, includes but is not limited to airand nitrogen. The application of the gas flow can begin prior to,during, or subsequent to the cooling step. In one embodiment, step 100comprises spraying a cryogenic liquid to the epidermal tissue region andstep 120 comprises removing cryogenic vapor formed through expansion ofthe cryogenic liquid. In this embodiment, application of the gas flowprevents flashing by removing both vapor molecules which chemicallyreact, reaction products which sustain further reaction, andcontaminants on the surface of the epidermal tissue which canparticipate as initiators.

Application of the gas flow can also beneficially contribute to coolingof the epidermal tissue region. In particular, application of the gasflow is believed to increase the speed at which the cryogenic liquidevaporates, and therefore increases the speed at which the epidermaltissue region is cooled. In another embodiment, the temperature of thegas flow is intentionally lowered to further reduce the temperature ofthe epidermal tissue region. The gas may be pre-cooled to below about20° C. The method of FIG. 5 can further include the step of post-coolingthe epidermal tissue region by applying a cryogenic fluid to theepidermal tissue region after the irradiation step (step 130). Thepost-cooling step can minimize damage to normal tissue caused byirradiation and accelerate healing of the treated tissue.

In one detailed embodiment, the irradiation step (step 120) takes placebetween 5 and 500 milliseconds after applying the cryogen to theepidermal tissue region. This delay period is sufficient to achieve thedesired low temperature profile in the epidermal tissue region. Thisdelay period, however, does not cause a light flash due to the removalstep (step 110). Without the removal step, this delay period is likelyto be sufficient for some cryogenic liquids such as R134a to vaporizeand react, thereby causing a light flash. However, with the removalstep, light flash is inhibited. In a preferred embodiment, theirradiation step takes place about 50 to 200 milliseconds after applyingthe cryogen to the epidermal tissue region.

In another embodiment, the method for performing a laser treatment ofskin, while preventing a light flash, comprises the steps shown in FIG.6. A first pulse of cryogenic fluid is applied to the epidermal tissueregion for a first time period (step 200). After waiting a delay periodof a predetermined time interval (step 210), a second pulse of cryogenicfluid is applied to the epidermal tissue region (step 220). In thisembodiment, the term “first pulse” refers to a first group of pulses,which may be one or more pulses. Likewise, the term “second pulse”refers to a second group of pulses, which may be one or more pulses. Theskin is irradiated to treat the dermal tissue region after theapplication of the second pulse of cryogenic (step 230). In one detailedembodiment, the second pulse of cryogenic fluid comprises a cryogenicliquid and the irradiation step takes place either during or immediatelyafter the application of the second pulse of cryogenic fluid. The secondpulse of cryogen inhibits the first pulse of cryogen from reacting andcreating a light flash. In addition, the application of the second pulseassists with cooling of the epidermal tissue region, and allows thefirst pulse of cryogenic fluid to be applied for a shorter time periodin order to achieve a desired low temperature profile for the epidermaltissue region.

In one detailed embodiment, the first pulse of cryogenic liquid issprayed to the epidermal tissue region for a time period ranging from 10to 150 milliseconds. The waiting period ranges from about 10 to about500 milliseconds. The second pulse of cryogenic liquid is sprayed to theepidermal tissue region for a time period ranging from 5 to 20milliseconds. The skin is irradiated within 5 milliseconds afterapplying the second pulse of liquid cryogen. In one example, a firstpulse of cryogenic liquid is applied for about 20 to 100 milliseconds,and after waiting 100 to 200 milliseconds, the second pulse of cryogenicliquid is applied for 5 to 20 milliseconds. In this example, skin isirradiated within 3 milliseconds of applying the second pulse ofcryogenic liquid.

In another embodiment, the method of performing laser treatmentcomprises the steps shown in FIG. 7. In this embodiment, the cryogenicfluid is first sprayed to the epidermal tissue region (step 300), andthe skin is irradiated to treat the dermal tissue region while thecryogen is still being sprayed to the epidermal tissue region (step310). In one detailed embodiment, the irradiation step begins before theliquid cryogen spray terminates. The method can further include the stepof post cooling the treated skin (step 320).

The present invention further contemplates the use of cryogen sourceswhich are less likely to cause a light flash. A conventional cryogensources such as R134a (tetrafluroethane) tends to dissociate quickly andcause a light flash. In one embodiment, a cryogen source comprises afluorocarbon compound where the ratio of fluorine to fluorine andhydrogen is equal to or greater than about 0.75. In another embodiment,a cryogen source comprises a fluorocarbon compound where the ratio ofchlorine and fluorine to chlorine, fluorine and hydrogen is equal to orgreater than about 0.75. In addition, the fluorocarbon compound has aboiling point of less than about 35° C. Examples of such compounds areprovided in the following table:

Enthalpy of Ratio of (Cl + BP vaporization Ratio of F)/(Cl + Name C H ClF (° C.) BTU/L; kJ/mol F/(F + H) F + H) Tetrafluoromethane 1 0 0 4 −1281 1 Hexafluoroethane 2 0 0 6 −78 50; 16 1 1 Octafluoropropane 3 0 0 8−38 45.28; 19 1 1 Chlorotrifuoromethane 1 0 0 3 −81 63; 15 1 1 (R13)Chloropentafluoroethane 2 0 1 5 −39 1 1 Dichlorodifluoromethane 1 0 2 2−30 68; 19 1 1 (R12) 1,2- 2 0 2 4 4 61.1; 24 1 1Dichlorotetrafluoroethane (R114) 1,1,1,2,3,3,3- 3 1 0 7 20 57; 22 0.880.88 Heptafluoropropane (R227ea) pentafluoroethane (R125) 2 1 0 5 −4961.5; 17 0.83 0.83 2-chloro-1,1,1,2,- 2 1 1 4 −12 71.3; 23 0.80 0.83tetrafluoroethane (R124) Trifluoromethane (R23) 1 1 0 3 −82 100; 16 0.750.75 1,1,1,2,3,3,- 3 2 0 6 7 0.75 0.75 Hexafluoropropane (R236ea)2,2,-dichloro-1,1,1,- 2 1 2 3 28 79.1; 28 0.75 0.83 trifluoroethane(R123)

Equivalents

While the invention has been particularly shown and described withreference to specific preferred embodiments, it should be understood bythose skilled in the art that various changes in form and detail may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims.

What is claimed is:
 1. A method for preventing a light flash duringradiation treatment of skin having an epidermal tissue region adjacent adermal tissue region, the method comprising: a) applying a cryogenicfluid to the epidermal tissue region; b) directing a gas flow in ageneral direction of the epidermal tissue region subsequent to step a)to remove at least a portion of the cryogenic fluid; and c) irradiatingthe skin with a radiation beam to treat the dermal tissue regionsubsequent to removing at least a portion of the cryogenic fluid.
 2. Themethod of claim 1 wherein step b) comprises directing a non-reactive gasflow in the general direction of the epidermal tissue region.
 3. Themethod of claim 2 wherein step b) comprises blowing air in the generaldirection of the epidermal tissue region.
 4. The method of claim 1wherein step c) comprises irradiating the skin for between about 5milliseconds and 500 milliseconds after applying the cryogenic fluid tothe epidermal tissue region.
 5. The method of claim 1 wherein step a)comprises applying a first pulse of cryogenic fluid to the epidermaltissue region for a first time period and waiting a predetermined delaybefore applying a second pulse of cryogenic fluid to the epidermaltissue region for a second time period.
 6. The method of claim 5 whereinthe delay period is in a range from about 10 milliseconds to about 500milliseconds.
 7. The method of claim 5 wherein the first time periodcomprises from about 20 milliseconds to 100 milliseconds and the secondtime period comprises from about 5 milliseconds to 20 milliseconds. 8.The method of claim 1 wherein step b) comprises removing a cryogenicvapor formed through evaporation of the cryogenic liquid.
 9. The methodof claim 1 wherein step b) comprises removing a plurality ofcontaminants over an outer surface of the epidermal tissue region. 10.The method of claim 1 wherein step b) comprises directing a gas flow ata rate of greater than about 10 liters per minute.
 11. The method ofclaim 1 further comprising pre-cooling the gas flow to a temperaturebelow about 20° C.
 12. The method of claim 1 wherein the cryogenic fluidcomprises a fluorocarbon compound.
 13. The method of claim 12 whereinthe fluorocarbon compound is selected from a group consisting of:tetrafluromethane; hexafluoroethane; octafluoropropane;chlorotrifluromethane; chloropentafluoroethane; dichlorodifluoromethane;1,2-dichlorotetrafluoroethane; 1,1,1,2,3,3,3,-heptafluoropropane;pentafluoroethane; 2-chloro-1,1,1,2- tetrafluoroethane;trifluoromethane; 1,1,1,2,3,3,-hexafluoropropane; and2,2-dichloro-1,1,1- trifluoroethane.
 14. The method of claim 1 whereinstep c) comprises irradiating with a laser light.
 15. The method ofclaim 1 further comprising d) postcooling the epidermal tissue region byapplying a cryogenic fluid to the epidermal tissue region after theirradiation step.
 16. A method for preventing light flash duringradiation treatment of skin having an epidermal tissue region adjacent adermal tissue region, the method comprising: a) applying a first pulseof cryogenic fluid to the epidermal tissue region for a first timeperiod; b) waiting a predetermined delay period before applying a secondpulse of cryogenic liquid to the epidermal tissue region for a secondtime period, the delay period being sufficient to allow the first pulseof cryogenic fluid to cool the epidermal tissue region to reach adesired temperature; and c) irradiating the skin to treat the dermaltissue region during or immediately after application of the secondpulse of cryogenic liquid.
 17. The method of claim 16 wherein step a)comprises spraying a cryogenic liquid to the epidermal tissue region fora time period in a range from about 10 milliseconds to 150 milliseconds.18. The method of claim 16 wherein step b) comprises spraying acryogenic liquid to the epidermal tissue region for a time period in arange from about 5 milliseconds to about 20 milliseconds.
 19. The methodof claim 16 wherein the delay period is in a range from about 10milliseconds to about 500 milliseconds.
 20. The method of claim 16wherein step c) comprising irradiating the skin within 5 milliseconds ofapplying the second pulse of cryogenic liquid.